In a PC, the central processing unit (CPU) is the primary control device for the entire computer system. The CPU is technically a set of components that manages all the activities and does much of the "heavy lifting" in a computer system. The CPU interfaces, or is connected, to all of the components such as memory, storage, and input/output (I/O) though communications channels called busses. The CPU performs a number of individual or discrete functions that must work in harmony in order for the system to function. Additionally, the CPU is responsible for managing the activities of the entire system. The CPU takes direction from internal commands that are stored in the CPU as well as external commands that come from the operating system and other programs. It is important to nore that these functions occur in all CPUs regardless of manufacturer

Today, often mistaken for the entire computer, case and all. CPU is NOT the entire computer but is the Central Processing Unit. It is the brain of computer executing tasks and telling the other components what to do. Mainly manufactured by AMD and Intel. the speed of the processor is measured in GHZ or MHZ (Gigahertz & Megahertz) for now anyway.

I recently upgraded my computers CPU from and AMD 2500+ (~1.8ghz)to a pentium IV 3.0 GHZ processor but I didn't notice much of a diffrence until I got some more RAM.

1. Central Processing Unit. The main part of your computer, (not your monitor or sound card, for example).
2. Cayce Pollard Units. From William Gibson's science fiction novel Pattern Recognition, non-brand-identifiable clothing: "things that could have been worn, to a general lack of comment, during any year between 1945 and 2000."

That hip consignment shop is all about CPU's--lots of basic black, and no logos.